Supplying power to a sliding door is relatively complex since, unlike with a rotatably operable hinged door, where common points independent from the door's open condition are automatically specified between the vehicle body and the hinged door, no independent common points are provided between the vehicle body and the door by the door's open condition. There exists, therefore, the need to create an electrical connection between electrical elements located on the sliding door and on the vehicle body, which enable a permanent reliable transmission of voltage and/or signals regardless of the door's open condition.
As is known, sliding doors are heavier than conventional hinged doors. On opening the sliding door, the point of gravity moves backwards in the longitudinal direction of the vehicle, which makes the sliding movement difficult, especially for older or disabled people and especially on uneven ground. Therefore, one endeavors to provide sliding doors with a motor-driven drive mechanism whereby, for production reasons, it may be preferable to house the drive motor for driving the sliding door in the sliding door itself. This requires a reliable, uninterrupted supply of power to the drive motor.
A reliable and uninterrupted supply of power to sliding doors is made difficult by the movement sequence during opening and closing since, as is known, when looked at from the longitudinal direction of the door, the guide rails provided on the top and bottom edge of the door aperture are curved on the front end to enable the sliding door to close substantially flush with the outer skin of the vehicle body in its closed position and so that in its open position it is guided at a distance to the outer skin of the vehicle body. For this purpose, sliding doors are usually pivotably hinged on guide carriages guided by the guide rails so that the sliding door is substantially parallel in all positions to a plane defined by the outer skin of the vehicle body. In addition to a movement in the sliding plane in the longitudinal direction of the vehicle, sliding doors thus execute a movement in a direction transverse to the sliding plane. A cable guide assembly for accommodating and guiding plus protecting the connecting electric cables is necessary so that the electric cables for supplying the sliding door with power do not snag or become caught up. Such cable guide assemblies must be designed so that they can accommodate or compensate the sliding door's sliding movement in the longitudinal direction of the vehicle as well as the sliding door's displacement transverse to the longitudinal direction of the vehicle. Various cable guide concepts are known from the prior art which will be described briefly in the following.
DE 197 17 490 A1 discloses a sliding door which is supplied by a supply cable that is wound onto a cable drum provided with a retraction device, wherein one end of the cable is connected to the drum core of the cable drum supported on the body side and the other end of the cable is connected to the sliding door. There is no provision for compensation of the displacement movement transverse to the longitudinal direction of the vehicle or to the sliding plane.
DE 100 00 930 A1 discloses an arrangement carrying electricity in a sliding door of a motor vehicle, with a guide rail, a sliding block which is accommodated in the guide rail so as to be sliding, and a cable harness that is attached to the sliding block and extends up to the vehicle body, whereby a section of the cable harness is formed in a curve between the sliding block and the body. The U-shaped, curved section of the cable harness spans the gap between the vehicle body and the sliding door, whereby there is no reliable way of preventing the cable harness from snagging.
DE 199 05 022 A1 discloses a sliding door according to the preamble of claim 1. The sliding door is capable of moving between an open position and a closed position in the longitudinal direction of the vehicle and includes a cable guide assembly designed as a cable drag chain in which electric cables are accommodated and guided. The cable drag chain's movement range is limited by a guide box provided in the vehicle's roof liner, in which the cable drag chain is accommodated and guided. The cable drag chain is only movable in a plane substantially coincident with the plane of the roof liner. This cable guiding concept requires additional provisions in the vehicle's roof liner which makes optional assembly of manually operated sliding doors and motor-driven sliding doors costly.